Serious chemical pollution from factories and chemical plants “aren’t concerns because we don’t have many reports, just isolated cases and leaks,” said Karen Timberlake, Wisconsin’s secretary of Health and Family Services.

Timberlake, who flew over much of her state’s flooded areas in a helicopter Wednesday, said hundreds of homes and acres of farmland are under water, roads are damaged and some towns’ water facilities are inundated.

But at least for now, she said, health concerns are rather mundane: “bacteria, stomach upset and (the possibility of) tetanus.”

The sole wastewater treatment plant in Cedar Rapids, Iowa, is inoperable, and Pat Ball, the city’s utilities director, said it won’t be up and running for months. That means raw sewage will continue spilling into the river and affect cities downstream, just as waste from damaged cities upstream continues to flow into Cedar Rapids’ water supply.

“Raw sewage exposure is always a concern, both from a health standpoint and from an environmental standpoint,” Ball said.

The pollution is most harmful to recreational users of the river, but many residential wells could be affected.

Officials at riverside industries – including Quaker and Cargill – were allowed to take hazardous-materials teams into their flooded plants before residents could return home to check for chemical spills. Ball said he wasn’t aware of any major spills.

Adam Broughton, an environmental specialist at the Iowa Department of Natural Resources, said residents have reported about 100 carcasses of farm animals as well as tanks containing propane and anhydrous ammonia and drums of unknown contents floating in waters or lodged under bridges.

A task force of National Guard troops and state and federal technicians will pick up the drums, test them and dispose of them as the fast-moving waters recede. More carcasses may be found as hog barns dry out, Broughton said.

“We can deal with as many (carcasses) as we have,” he said. “We can bury thousands, if necessary.”

Nancy Hall, a supervisor at University Hygienic Laboratories, Iowa’s environmental laboratory, said levels of E. coli bacteria jumped from pre-flood levels ranging from a few hundred or thousands per 100 milliliters to a few tens of thousands or hundreds of thousands per 100 milliliters.

Levels considered safe are zero for drinking water and 126 per 100 milliliters at a beach.

“So the water could contain microorganisms that could make us sick,” Hall said.

The results of chemical testing will be available in a week. If experience is a guide, Hall said there may be little to worry about. The flood of 1993 showed “small amounts” of pesticides, herbicides and other chemicals in the water, but no illnesses as a result, she said.